Many investigators have observed that mutagens and carcinogens may be covalently bound to DNA; however, no investigations to our knowledge have looked at the effect of base sequence on binding. Thus, we compared the amount of binding of the direct acting carcinogen N acetoxy-2-aminofluorene with four synthetic double-stranded polymers of known sequence. At extents of reaction of one percent or greater, poly(dG-dC) was attacked 2-3 times as readily as poly(dG).poly(dC) and both were attacked much more readily than polymers containing AT. At very low extensive reaction the attack on the two GC containing polymers was about equal, suggesting that at higher levels of attack there was some positive interaction between the first molecule bound and additional attacking carcinogen molecules.